Artificial horizon



E. G. FISCHER. ART`|F|c|AL HoRlzoN.

APPLICATION FILED IAN-29,1921.

1,386,695. f. Patented Aug. 9,1921.

2 SHEETS-SHEET l.

INVENTOR Erl/761" Gf F'A'Scher.

E. G. FISCHER.

ARTIFICIAL HORIZON.

A'PPLlcMloN FILED 1AN.29. 192|.

INVENTOR 2 SHEETS-SHEET 2- Patented Aug. 9, 1921..

' nniranrarss FTNT QFFICE,

ARTIFICIAL HORIZON.

Specication of Letters Patent.

v Application filed January 29, 1921. Serial No. 441,001.

T 0 @ZZ cli/wm t may concern:

Be it known that I, ERNST G. FISCHER, a citizen of the United States, residing at Vilashington, in the District of Columbia, have invented anew and Improved Artificial Horizon, of Which thev following is a speciication. y

This invention ha'sfor its object to provide an artificialv horizonyfor sextants, hand or mounted levels, and other surveying and astronomical apparatus requiring exact definition of either the horizon or vertical.

Generically the invention comprises a pendulum device containing a pair of pendulum-vanes, one of Which has a horizon line which is cooperative with another horizon line that is relatively ixedly mounted on the instrument, the other pendulum-vane having a point Which coperates with the horizon lines` allbemg arranged Vso that when the instrument is held in the true vertical position and in a position to bring both horizon lines in longitudinal alinement, the point will appear in a central position With relation to the horizon lines and the horizon lines Will then correspond to the true horizon. V

In its morespeciic nature, the invention includes pendulum-vanes of relatively small mass and large area (suspended in a manner to reduce bearing friction to the minimum), in its motions opposed to air or a suitable liquid so that the oscillations of the pendulum-vanes are damped and as nearly deadbeat as is practicable, yet sensitiveto the smallest departure from the normal; a small light arm being attached toone pendulumvane and carrying a piece of line platinum Wire m'ounted horizontally, there being a small piece of platinum Wire fixed to the apparatus supporting the pendulum-vane in such manner that, when adjusted, and the vane is at rest, the Wires are in longitudinal alinement. Y

The other vane Valso carries a piece of fine platinum Wire having its free end located in proximity to the-horizon line Wires in suchmanner that, when adjusted and the vane is at rest, the end of said last named Wire Will he centrally disposed With relation to the horizon Wires and assure `the verticality lof the plane `in which an angle above the horizon is to be measured.

Inasmuch as my invention has been eS- pecially designed for use in connection with the sextant, I have illustrated the invention as applied to such an instrument and shall describe the same in that relation, although I lWish it understood that, in its use, the invention is not limited to sextants but may be employed Wherever a device of this nature is found useful. Y

In its more subordinate nature, the invention also includes those novel details of construction, combination and arrangement of parts, all of which will be irst fully described and then be specifically pointed out in the appended claims, reference being had to the accompanying drawings, in which:

Figure l is an elevation of a sextant With the invention applied. y

Fig. 2 is an enlarged vertical longitudinal section of the invention. y

Fig.` 3 is a reduced transverse section on the line 3-3 of Fig. 2, looking in the direction of the arrow.

Fig. 4 is an enlarged elevation of the capk disk which supports the operative parts of the pendulum mechanism.

Fig. 5 is a det-ail perspective view of the pendulum mechanism and the bracket Which supports the same.

Fig. 6 isfan enlarged tion 'of the same.

Fig. 7 is a vertical central longitudinal detail vieiv of a porsection of a portion of the mechanism shownV in Fig. 5.

Fig. 8 is a vmagnified view of the image visible through the eye piece, When the true horizon is indicated.

In the drawings in which like numerals ot' reference designate like parts in all of the figures, l represents the sextant which is of the ordinary construction and, per se, forms no part of the present invention. Therefore,

a detailed description of the same is thought to be unnecessary.

vSecured .to the plate 3 is a holder 5 in- `vvhich a tube 6' is suitably mounted. The

Patented Augfl, 1921;

' forward end ofthe tube 6 ris providedwith a collimating lens 7 which is so mounted that its principal focus lies 1n the horizon wires 'of the device hereinafter again referred to.

At the outer end ofthe tube'is mounteda pendulum device which constitutes the essential part of the present invention. rEhis device consists of areceptacle 12 mounted on the end of the tube 6 and Vvhaving a' chamber in communication with the interior of the tube 6, the holder having a collar into which 2 the tube flits.

The chamber' in the receptacle 12 is vided for thejpendulum-vane 24.

. 13 is the; disk or cap plate for the recepprof j tacle 12on which plate the pendulum appa- A-ratusfis mounted.'y The cap 13 is secured by screws, as indicated; f

Thetube 6 is provided with a window 8 that is mounted in an inwardly projecting collar, so constructed as to-prevent the acv c'umulation of air bubbles on the glass of the `medium.- 1

window, when liquid is used as a dampening f Adjacentto the vided'withga transparent partition 31, when liquid isv used.asadampening medium, to

retain Vthe lliquid in the forward end ofthe tube; 'n f` r,10 is a lamp socket mounted on a clip yh lder`9that clips over the tubefholder 5 and can be turned about the axis of the tube (see Fig. 3) so that the bulb will be brought with its transparent portion 11, to register with the window or bemoved to one side out of register with the same (see dotted lines 'Fig it beingunderstood that 'the bulb is preferably rendered opaque except for the area 11 directly above the window 8, when the parts are positioned` asV indicated in Figs. 1 and 2. y T he illuminating-powerfor the lamp canl be obtained from' any desired source, either by a battery in the handle of the sextant or in any other desired way.

f By referring more particularlyto Figs. 2 to 7, inclusive, the construction and manner of mounting the pendulum-vanes will be clearl l V`15 designates 'a bracket body having knife bearingV lugs V17 'projecting from the same, the lugs having I\./grooves VVto receive the "knife ends 18, which are connected by the cross bar 20.

- The knife bearing endsv are Vbeveled (see Fig. 6) so that onlya point will be presented to the end plates 21fat the pivotal axis vofithe pendulum to prevent lateral displacement of the bearing knives their grooves.

The end plates21 haveears 22apertured and securedby screws to the bracket 15,- the plates 21 lying against the bearing projections 17Mattheends of the knife bar, as

shown. z'lheyl areV preferably ofy greater depth than the depth of the bearing projecwindow 8,v the tube is protions, soy as vto form stops.. 32 tozprevent the knives 18 fallingout of the 'grooves 26, when the instrument is inverted or j arred.

The bracket The knife bar 20 is provided with a pluby Vbendingthe same around the bar 20, a third notch .being provided to receive the end of the arm A26, which is rigidly secured to the bar 2() and projects into the tube 6, the armv 26 being provided, at its forward end, with a socket to-fholdk a inewire 27 preferably.

33 designates an extension bracket which body 15 issecured at 16 to rality of recesses 23 (see Fig. 6) in which the varms 25, of the pendulum-vane 24 are held is secured kto the bracket 15- and is provided with bearing recessesV 34 and 35j,V the latter being contained inan adjustable screw for l taking up wear, the bearings 34 and 35 :be-

ing'adapted to sustainfa spindle 36 havingv its ends pointed to bear-in the bearings 34 and 35 andfso positioned thatitsA axis will be in a verticalplane. andinclined atf'anfangle of preferably forty-ive degrees to the hori- Zontal..V Y Y The bracket 33VisV 4located centrally ,be. i

tween the bearing Vlugs 17 andl between theV arms 26 .and 28, as best shown'in Figs.'v 4, 5and7.

small mass andgreat area. jfllhe vaneg37 is adapted to lie between thefarms 26an'd' 28 and'ris'V secured to .thev spindle 36` the vane 37 being adapted vto swing its yforward end r37 is a second pendulum-vane of relatively toward'. one/or the other ofthe arms 26 or 28 accordingly asfthe instrumenti's tilted L to one side or the other-of the vertical. v The vane V37 is provided: with a -line wire 38, preferablyof platinum, which is extended out .into close proximity to 'the wires'27 and Y 3() and it has its end turned over,1as at39, for a purpose presently explained.l

ln order-'not tointerfere-with the-up and downmoveinent of the wire 27, due to the.r

movements vof the pendulum vane124, the curled overend 39' ofthe-wire 38 does'not extend entirely tothe :plane-Tin which the wire 27 movesup and fdown,a but lies sufficiently 'close thereto so thatthepoint at which the light` entering through the 4.window 8 strikes the curled overv end ofthe wireV 38' and also; strikesthe wires 30 and v27, gwill' be at substantially theprincipalfocusr ofv the lens. v

In use, the light from the lamp is directed through the window 48 onto the wires 27 and 30 Vand the end 39 of wire 38 and transmitted as parallel rays by the lens 7 to the telescope of the seXtant.

In' daylight observations, the necessary light may be admitted through the window from the sky and, inI that event, the lamp is :moved to the dotted position shown in Fia- 3, so as to expose the window 8.

duct 14 is provided for delivering the liquid into the chamber in the receptacle 12 and linto the end of the tube 6 forward of the partition 31, when it is desired to use liquid as the dampening medium, the duct 14 being closed by a removable cap.

In the preferred construction, the chamber in the receptacle 12 and tube 6 is substantially filled with a suitable limpid nonfreezable oil, the oil being confined by the transparent partition 31.

The amount of dampening desired, either in air or in liquid, canl be varied by varying the area of the vanes; the width of the space or clearance between the edges and sides of the containing chamber in which the vane 24 is located and the space between the faces of this vane and the walls of the chamber against which it swings, may also be varied to vary the amount of dampening.

In order to limit the movement of the vane 37, a fork 40 is provided, which straddles the vane and is secured at 41 to the bracket 38, the ends of the fork being spread apart the desired distance to allow the vane 37 suiiicient motion for its purposes.

F1-omthe foregoing, it will be observed that, when the sextant is held inthe true vertical and horizontal position, the wires 27 and 30 will be in longitudinal alinement as indicatedinvFig. 8 and the end 39 of the wire 3S will appear in the vision as a ldot lying'midwaybetween the'lines 27 and 30 but above or below the same according as` toy whether the wire 38 is so positioned that the point of contact of the light rays entering through the window will strike the curled end 39 below or above the axis of the wire 30.

Then thewires 27 and 30 and the dot 39 appear in the vision, as shown in full lines -in Fig. 8 the lines 27 and 30 are'in the position of the true horizon, and this combined line 27-30 constitutes the artificial horizon. The seXtant arm is then adjusted to bring the image of the celestial or terrestrial ob- `iect, either in contact with or bisected by this horizon line, whereupon the reading of the vernier on the arc will give the altitude of the body observed.

The dotted lines and dots in Fig. 8 indicate the movements of the wire 27 and the dot 38, depending upon the inclination of the instrument.

The present invention constitutes an improvement on the apparatusshown and described in my lapplication Serial No. 801,920 filed June 5, 1919, and in this application I lay no claim, per se, to the matter shown and described in my former application and claimed in the same.

F rom the foregoing description, taken in connection with the accompanying drawings, it is thought the complete operation and uses of myinvention will be readily understood by those skilled in the art.

What I claim is:

l. A device of the character described support,` a relatively fixed indicator line mounted 'on the support, a second indicator line carried by one of said pendulumvanesand a third indicator line carried by the otherpendulum-vane, a coliimating lens carried by the support, said iirst and second lines being positioned to lie in axial alinement substantially passing through the principal focus of said lens when the instrument is in ,.-the horizontal position, the end of the third of said lines being positioned to lie in close proximity to said first and second lines7 and substantially in the principal focus of said lens, when the instrument is in the true horizontal and vertical positions, and means by which said lines may be illuminated' to cause their image to Vbe transmitted through the collimating lens.

,8. A device oi2 the character described ccmprising a support, pendulum-vanes mounted on said support, a line relatively fixed with regard tovsaid support, and otherlines carried by said pendulum-varies and coperative one with the other and each with said fixed line Vfor the purposes specified, such lines lying in close proximity to one another. l

4. Ina device of the character described, a support, pendulum-vanes mounted on said support to lie with their axes at right angles, a relatively fixed indicator linc7 andv indicator lines carried by said pendulum-vanes to coperate with said fixed lines for the purposes specified.

5. In a device of the character described, a support, pendulum-vanes mounted on said support to lie with their axes at right angles, 'a relatively fixed indicator line and iniso reses-ei.

` for limiting the swing of said pendulum-r` angles toits axis, another pendulum having an indicating element the indicating Yportion y ot. which lies in proximity to,said'linesfr7 said other pendulum adapted to move its in.

mounted on said support, a line carriedby said pendulum-vane and a line relatively fixed With regard to said Vsupportand co- Y Yoperative with said pendulum carried iline to constitute an artiicial horizon line, a

second ypendulum-vane mounted lon said sup-v port, a line2 carried by said second'pendulum-vane and having an `end located in close proximity to said. aforementioned lines and cooperative withV said lines to determine the true horizontal and-vertical position of the instrument,.said vanes comprising thin bodies ot relatively large area opposed to the direction ot movement, said bodies being of:V

' bearings and vlying substantially `normalrto` one another, a tixedarni carriedfby said support and fprojectin-g inthe longitudinal f direction' got. one of'said vanes, an'. arm on vthev other ot' :said penduluinfvanes also vprosmall mass. l

7. In a device of the character described,` a housing?,- inc/losing a chamber, a bracketI mounted Within the housing and having bearings, a pendulum-vane mountedr on said bearings4 an indicator operativeV with Vsaid pendulum-vane, a second indicator relatively z fixed and coperating` with said firstV nien- .tioned indicator -to' constitute an-` 'artificiale horizon line, a second bracket having .bearingaa second lrindicator vane mounted Vin said bearings-and having an indicator movable adjacent to said first and second indicators to cooperate with the same.

8. In a device of the character described, a housing` inclosing a chamber, a bracket. mounted Within the housing and.; having bearings, a pendulum-vane mounted on said...

bearings, an indicatoroperative with said VVpendulum-vane, a second indicator relatively fixed and cooperating With said iirst mentioned indicator to, constitute an artiicial horizon line, a second braclretjhaving bearings, Aa second indicator vane mounted in said bearings and having an indicator movf.

ableV adjacent to saidrst and 4second indicators tocoperate with the same, and means vanes between predetermined limits.

9. In a device of the .character described,

a support having` tivo sets ot bearings, pendirection of one of said vanes, an armonthe other of said pendulum-vanos also pro]ect` ing in the longitudinal direction of' said one pendulum-vane, indicators carried by said arms, and an indicator carried by said one n pendulumsvane, said. indicators lying proximity-jto one another for the purposes desc-ribed l io. 'in a devies retir character described,

a *support ,having two set-sof bearings, -penduluni-vanes, one mounted in each@ set ot bearingsY and 'j lying. vsubstantially normal to one another, a tixedgarmlcarried by said support and proyecting, infthe longitudinal. direction: of .one of' said vanes,.an arm on' the other ot said pendulum-vanos also projecting in the longitudinaldirectionotsaid one pendulum-vane, indicators carried fbyv` said a'rm's,' aiidV` an indicator carried by said one penduluinsvane, saidindicators lyingin :proximity to one` another, andy means ffor limiting the movements Vvoff-said pendulurm vl1. lniadevicfe of the character describedyry a support having two sets of bearings, pendulum-varies,.onemounted in each vset ot )ecting in the longitudinal direction oifsaidone pendulum-vane, indicators'` carried by". l said arms, andvanindicator carried by said.- one pendulum-vane, said indicators-lying in:

secured to said support to limit'theinove..

a fixed horizonline ainovable horizon line and a p \.ndulum for. movingV said'movable lhorizon hneimadirectionat right angles to its' axis., another penduluinhaviiig an indicating elementthe indicating portion;

of which liesinaproximity to'saidl linesf-7 said other pendulumlvadapted to'inove its in-` 'e Y. I cheatingelement infa direction substantially.

parallel tothe axis oit said lines, substan-J tially. as shown. anddescrib,ed. I u 13. In a deviceV of thecharacter described,

Yaf -iixed horizon linefiv a '.movable4 horizonl able horizon fline7 in a direction atV right dicating` element iny aedirectionsubstantially mitted .through the collimating lens,said.

horizon lines and the indicating portionH ot said other pendulum fliner lying -substantially inthe principal focus of said lens.

. ERNsr Girone, insonnia..

izo 

